Essential Oil Constituents of Echinophora platyloba DC.

The hydrodistilled oil of the aerial parts of Echiophora platyloba DC. was analyzed by GC and GC/MS. Ten components have been identified, of which the major constituents were found to be trans-b -ocimene (67.9%), 2-furanone (6.2%), myrcene (6.0%), linalool (3.1%), and cis-b -ocimene (2.3%).

The hydrodistilled oil of the aerial parts of Echiophora platyloba DC. was analyzed by GC and GC/MS. Ten components have been identified, of which the major constituents were found to be trans-b
-ocimene (67.9%), 2-furanone (6.2%), myrcene (6.0%), linalool (3.1%), and cis-b
-ocimene (2.3%).

The genus Echinophora is (Umbelliferae, subfamily Apioideae, tribe Echinophoreae) represented in the flora of Iran by four species including two endemics (1-3). These are: E. sibthorpiana Guss., E orientalis Hedge et Lamond and two endemic species, which are E. platyloba DC. and E. cinerea (Boiss.) Hedge et Lamond (2). In Iran, fresh and dried aerial parts of some of these species are added to cheese and yoghurt for flavoring. The genus Echinophora has been the subject of scant phytochemical and biological investigations. E.platyloba is locally known as "Khosharizeh" (2). A view of literature has not revealed any previous work on the oil of E. platyloba. However, oils from other Echinophora species have been the subject of several studies (4-11). The plant is one of the Iranian endemic species, which could be found in some central and western provinces of the country (12).

Experimental

Collection of plant materials

Aerial parts of the plant were collected from Alvand Mountain, Golpaygan-Khomein Road, at an altitude of 1750 m on June 1999. Voucher specimens of the plant (E25) are available at the Herbarium of the Faculty of Pharmacy and Pharmaceutical Sciences, Isfahan University of Medical Sciences, Isfahan, I.R. Iran.

Air-dried aerial parts of E. platyloba were ground and subjected to hydrodistillation for 4 h, using Clevenger-type apparatus.

Analysis

Gas chromatography analysis was carried out on a Perkin-Elmer 8500 gas chromatograph with FID detector and a BP-1 capillary column (39 m x 0.25 mm; film thickness 0.25 m
m). The carrier gas was helium with a flow rate of 2 ml/min. The oven temperature for the first 4 min was kept at 60°
C and then increased at a rate of 4°
C/min until reached a temperature of 280°
C. Injector and detector temperatures were also set at 280°
C.

Identification of constituents present was based on computer matching against the library spectra (Wiley275L), built up using pure substances and components of known constituents, MS literature data and evaluation of fragmentation patterns of compounds and their confirmation by gas chromatography retention times (13). The percentage of essential oil composition was computed from gas chromatography peak areas, without using correction factors. A series of hydrocarbon standards (C9-C18) were also used to calculate Kovats indices from the gas chromatography analysis. Kovats indices were calculated by the Kovats equation. Identification was based on retention indices and comparison of mass spectra with the literature (13, 14).

Results and Discussion

Results of chromatographic analysis of E. platyloba oil are presented in Table 1.

No.

Compound

Percentage

Retention Index

1

2-butenal

1.8

870

2

myrcene

6.0

989

3

ρ

-cymene

1.2

1021

4

limonene

1.5

1025

5

cis-b
-ocimene

2.3

1034

6

trans-b
-ocimene

67.9

1047

7

unknown

1.4

1095

8

linalool

3.1

1098

9

ρ

-mentha-1,5,8-triene

1.5

1127

10

unknown

2.2

1207

11

cis-3-hexenyl 2-methyl butanoate

2.0

1229

12

unknown

2.9

1271

13

2-furanone

6.2

1466

The identified constituents were 2-butenal, myrcene,

ρ-cymene, limonene, cis-b
-ocimene, trans-b
-ocimene, linalool, ρ-mentha-1, 5, 8-triene, cis-3-hexenyl 2-methyl butanoate, and 2-furanone. Trans-b
-ocimene (67.9%) was the main constituent of the oil and the major components were 2-furanone (6.2%), myrcene (6.0%), linalool (3.1%), and cis-b
-ocimene (2.3%). Earlier reports indicated that E. sibthorpiana contains methyl eugenol and E. lamondiana contains d
-3-carene as the major constituents of their oils (10, 11). In the E. chrysantha oil,a
-phellandrene was identified as the major compound (15).

The composition of E. platyloba oil was found to be rich in monoterpenes (83.5%), with a predominance of hydrocarbons (80.4%). The essential oil of E. platyloba could be considered as a source of hydrocarbon monoterpenes, especiallythetrans-b
-ocimene

Acknowledgment

This work was financially supported by the research council of the Isfahan University of Medical Sciences.